The present invention relates to a solid-state image pickup device and relates to a column circuit which is provided corresponding to, for example, each column of a pixel array.
The solid-state image pickup device (also called an image sensor) includes the pixel array that a plurality of pixels are arrayed in a matrix. A vertical signal line is provided corresponding to each column of the pixel array. In case of a CMOS (Complementary Metal Oxide Semiconductor) image sensor, each pixel includes at least one photoelectric conversion element and an amplification transistor which outputs an electric signal according to charges stored in the photoelectric conversion element to the vertical signal line.
In the CMOS image sensor, the column circuits are provided respectively corresponding to the columns of the pixel array. Each column circuit is provided with a current source transistor for defining a current flowing through the corresponding vertical signal line. A source follower circuit is configured by the current source transistor and the amplification transistor of each pixel. A bias voltage is applied from a common bias circuit to a control electrode of each current source transistor (see, for example, Japanese Unexamined Patent Application Publication No. 2012-253691).